Ignition distributor



1963 H. J. CROMWELL 3, ,803

IGNITION DISTRIBUTOR Filed July 28, 1961 2 Sheets-Sheet 2 INVENTOR.Harold J. Cromwell F g. 5

# ARM- United States Patent Ofiiice 3,114,803 Patented Dec. 17, 19633,114,893 IGNITION DISTRIBUTUR Harold J. Cromwell, Anderson, Ind,assignor to General Motors Corporation, Detroit, Mich, a corporation ofDelaware Filed July 28, 1961, Ser. No. 127,598 12 Claims. (Cl. 200-30)This invention relates to an ignition distributor for controlling thespark timing in an ignition system of an internal combustion engine.

In ignition distributors it is necessary to maintain a given effectivedistance between the adjacent terminals in the distributor cap so as toprevent electrical leakage between the terminals of the cap or betweenthe contact on a distributor rotor to the incorrect terminal in the cap.The distance required between corresponding terminals depends on thepeak voltage handled.

In order to prevent the high voltage handled by the distributor fromjumping to the incorrect terminal, it is desirable that the rotor becorrectly aligned with the correct terminal in the cap when the voltageis to be impressed on a particular spark plug. This condition ismaintained on certain model of distributors by the centrifugal advancemechanism because the cam and rotor of the distributor rotate as a unit.However, this con dition is not maintained during vacuum advance on mostdistributors, because the breaker contacts and consequently the sparktiming are shifted relative to the cap. If this latter condition couldbe corrected, the size of the present distributor could be reduced andif desired could be used to handle higher voltage than is now possible.

It accordingly it one of the objects of this invention to provide adistributor apparatus wherein the vacuum advance mechanism will notalter the correct functioning of spark distribution to the correctelectrode or terminal in the distributor cap.

A more specific object of this invention is to provide the distributorcap with an insert that is rotatable with respect to the cap and whichhas contacts that engage the terminals of the distributor cap, theinsert being mechanically connected to rotate with the breaker plate ofthe distributor whereby the insert is shifted during vacuum advance.

Another object of this invention is to provide a distributor cap with aninsert member that is formed of insulating material and which carries aplurality of generally arcuately extending contacts that slidably engagethe terminals of the distributor cap, the insert member being connectedwith the breaker plate of the distributor by an upstanding arm which issecured to the breaker plate and to the insert member.

*Further objects and advantages of the present invention will beapparent from the following description, reference being had to theaccompanying drawings Wherein a preferred embodiment of the presentinvention is clearly shown.

In the drawings:

FIGURE 1 is a sectional view of a distributor made in accordance withthis invention.

FIGURE 2 is a sectional view taken along line 2-2 I to FIGURE 1, thereference numeral .10 designates the base of a distributor. The base 19has a central bore which receives a bearing 12 in which is journalledthe shaft 14. The base it; may extend downwardly for a considerabledistance as is well known to those skilled in the art and anotherbearing or bushing may be supported in the lower end of the base 10 tojournal the shaft 14 in its rotation. The shaft 14 is, of course, drivenby the internal combustion engine on which the distributor is used.

Fitted on the shaft 14 is a conventional cam member 16 which is drivenby and slightly rotatable with respect to the shaft 14 and which isconnected with a plate member 18 which forms a part of a conventionalcontrifugal advance mechanism generally designated by reference nu meral20. This centrifugal advance mechanism may be of the type illustrated inthe Hartzell et a1. Patent 2,872,- 537. This centrifugal advancemechanism, as is well known to those skilled in the art, will adjust thecam member 16 relative to the shaft 14 in accordance with the speed ofrotation of the shaft 14.

The part 13 that forms a portion of the centrifugal advance mechanism 2dsupports a rotor which is generally designated by reference numeral 22.This rotor is conventional and is formed of part 24 that carriesoverlapping electrodes .26 and 28. The part 24 as is well known to thoseskilled in the art, is formed of insulating material and the electrode26 is a spring metal electrode. The rotor 22 is secured to the part 18by fasteners 27 and this part of the distributor is all of conventionalconstruction.

The top end of bushing 12 journals a breaker plate which is designatedby reference numeral 30. The breaker plate 3%} is rotated with respectto the bushing '12 by a vacuum unit 32 having a rod 34 formed with anupturned portion 36that passes through an opening in the breaker plate30. The vacuum unit 32 contains the usual diaphragm, not shown, forshifting the rod 34 and the usual spring for urging the diaphragm in onedirection. This vacuum unit is conventional and may be of the typeillustrated in the above noted Hartzell et al. Patent 2,872,537.

The breaker plate 30 canries the usual contact set designated in itsentirely by reference numeral 38. This contact set is secured to thebreaker plate 30 to rotate therewith and includes a breaker arm 40pivotally supported on a post 42. The breaker arm 40 carries a breakercontact 44 which cooperates with a fixed breaker contact 46. The breakerarm 40 carries a rubbing block 48 which cooperates with the cam 16 in amanner well known to those skilled in the art. It is seen that as thevacuum unit adjusts the breaker plate 30 around the axis of the shaft14, the spark timing of the distributor is adjusted since the contactset 38 which moves with the breaker plate 30 will be adjusted relativeto the cam 16.

The distributor cap for the distributor of this invention is designatedin its entirety by the reference numeral 50. This distributor cap isformed of a moldable plastic material and has a plurality ofcircumferentially spaced electrodes or terminals 52 which are to beconnected by suitable leads with the spark plugs on an internalcombustion engine. For an eight cylinder engine there will be eightequally spaced electrodes 52 in the distributor cap. The lower ends 52aof the terminals 52 are machined or otherwise formed flat for thepurpose to be more fully described hereinafter. The distributor cap hasa center electrode or terminal 54 including a ball contact 56 whichengages the portion 58 of spring metal contact 26. As the rotor 22rotates the ball contact 56 is in constant engagement with the portion58 of the spring metal contactor 26.

The center electrode 54 of the distributor cap 59 pivotally supports aninsert member generally designated by reference numeral 64}. This insertmember is better illustrated in FIGURES 3 through 5 and has a bodyportion 62 formed of a moldable plastic material. The body portion 62carries eight terminals or electrodes '64-, that have the same spacingas the terminals or electrodes 52 of the distributor cap 50. The topside of the terminals 64 are machined or otherwise formed flat and aregenerally arcuately shaped as is apparent from an inspection of FIGURE3. The terminals 64 project through the body portion 62 of the insertmember 69 and the lower ends of these contacts are cut away to formgenerally arcuately extending walls 64b. The body portion 62 of theinsert member 6!) is shaped to provide a slot 66 and to provide annularslots 68 and 70. The body portion is also formed with an upstandingannular skirt section 72 as is clearly apparent from the drawings.

The insert member 69' has a central opening 74 which receives the centerelectrode 54 of the distributor cap 59. The center electrode 54 carriesa retainer 76 and a spring 78 is interposed between the retainer and theinsert member 69. A downwardly projecting portion 86 of the distributorcap fits within the annular slot 70 of the insert 60. The fiat surfaces64a of the contact 64 engage the flat surfaces 52a on the terminals orelectrodes 52 located in the distributor cap. The surfaces 64a are ofsufiicient length so that contact is maintained between the terminals 52and 64 even though the insert 60 is rotated to some extent.

It can be seen that with the arrangement that has just been describedthe insert member 68 is rotatably supported by the center electrode 54-and that spark impulses are transferred between the center electrode 54and the electrodes 52 of the distributor cap by the rotor contacts 26and 28. In this connection, it is seen that the end of rotor contact 28passes in close proximity to the arcuate Walls 64b of the terminals 64.

The insert member 69 is mechanically connected with the breaker plate 30so that they rotate together. T this end, a bracket member 82 is securedto the breaker plate 30 by means of a screw fastener 84. The bracketmember 84 carries an arm 86 which is riveted or otherwise secured to thebracket member 82. The top end 88 of the arm member 86 fits within theslot 66 formed in the insert member 60 and it therefore is seen that asthe breaker plate 38 rotates the insert member 6d is rotated therewith.It will be apparent that other means might be used to connect thebreaker plate 3% and the insert member 60 Without departing from thespirit and scope of this invention.

It can be seen that with the use of the insert member 60 the correctelectrode or terminal of the distributor cap th is maintained connectedwith the center electrode 54 by the rotor contacts 26 and 28 even thoughthe spark is advanced by a shiftable movement of the breaker plate 39.This is true since the insert member 60' must rotate at all times withthe breaker plate 3b and contact is maintained between the terminals 52of the distributor cap and the terminals 64 of the insert due to theelongated surfaces 6442 of the terminals 64. As has been pointed outabove, the use of the insert member permits a reduction in size of thedistributor and also permits the use of higher voltages for the ignitionsystem.

While the embodiment of the invention as herein disclosed constitutes apreferred form, it is to be understood that other forms might beadopted.

What is claimed is as follows:

1. An ignition distributor comprising, a base member, a shaft journalledfor rotation in said base member, a breaker plate shiftable relative tosaid base member carrying breaker Contact apparatus, a cam member drivenby said shaft cooperating with said breaker contact apparatus, a rotormember driven by said shaft having contact means, a distributor capcarried by said base member including a projecting current carryingcenter electrode and a plurality of outer circumferentially spacedelectrodes, an ins rt member formed of electrical insulating materialhaving an opening receiving said center electrode whereby said insertmember is supported for rotation on said center electrode of saiddistributor cap, said insert member having a plurality ofcircumferentially spaced electrodes that are in engagement with theouter circumferentially spaced electrodes of said distributor cap, thecontact means of said rotor being electrically connected with saidcenter electrode and swinging in close proximity to portions of theelectrodes of said insert member, and means mechanically connecting saidbreaker plate and said insert member whereby they move together.

2. A11 ignition distributor comprising, a base member,- a shaftrotatable with respect to said base member, a breaker plate shiftablerelative to said base member carrying breaker contact apparatus, a cammember rotatably driven by said shaft cooperating with said breakercontact apparatus, a rotor member including contact means driven by saidshaft, a distributor cap supported by said base member including acenter electrode and a plurality of outer circumferentially spacedelectrodes, said contact means on said rotor member being electricallyconnected with the center electrode of said distributor cap when saiddistributor cap is in place on said base member, an insert memberrotatably supported by means fixed with respect to said distributor capincluding a body member formed of electrical insulating material whichsupports a plurality of circumferentially spaced electrodes that are insliding engagement with the outer circumferentially spaced electrodes ofsaid distributor cap, and separable connecting means connecting saidbreaker plate and said insert member, and an opening in said insertmember, said center electrode projecting through said opening to makesaid electrical connection with said contact means of said rotor member.

3. An ignition distributor comprising, a base member, a shaft rotatablewith respect to said base member, a breaker plate carrying breakercontact apparatus shiftaole relative to said base member, a cam memberrotatably driven by said shaft cooperating with said breaker contactapparatus, a rotor member driven by said shaft including contact means,a distributor cap supported by said base member formed of a plasticinsulating material and carrying a center electrode and a plurality ofouter circumferentially spaced electrodes, the contact means of saidrotor being electrically connected with the center electrode of saiddistributor cap, an insert member formed of electric insulating materialrotatably supported by means fixed with respect to said distributor capand carrying a plurality of circumferentially spaced electrodes that arein engagement with the electrodes of said distributor cap, said insertmember having an opening receiving said center electrode of saiddistributor cap, the electrodes of said insert member electricallyconnecting the contact means of said rotor with the outer electrodes ofsaid distributor cap, slot means formed in said insert member, and armmeans connected with said breaker plate fitting within the slot means ofsaid insert member whereby said insert member and breaker plate areseparably connected.

4. An ignition distributor comprising, a base member, a shaft rotatablewith respect to said base member, a breaker plate shiftable relative tosaid shaft carrying breaker contact apparatus, a cam member driven bysaid shaft cooperating with said breaker contact apparatus, a rotormember driven by said shaft positioned above said cam member, said rotormember carrying contact means, a distributor cap supported by said basemember including a current carrying center electrode and a plurality ofouter circumferentially spaced electrodes, an insert member formed ofelectric insulating material having an opening receiving said centerelectrode whereby said insert member is rotatably supported directly onthe center electrode of said dist ibutor cap and positioned between saidrotor and the top wall of said distributor cap, said in sert membercarrying a plurality of circumferentially spaced electrodes that are inengagement with the outer circumferentially spaced electrodes of saiddistributor cap and having projecting portions located in closeproximity to the contact means of said rotor member, and arm meansconnected with said breaker plate and extending upwardly into engagementwith said insert member whereby said breaker plate and insert membermove as a unit.

5. A distributor cap for an ignition distributor comprising, a bodyportion formed of electric insulating material, said body portionsupporting a current carrying center electrode and a plurality ofcircumferentially spaced outer electrodes, and an insert member formedof electric insulating material rotatably supported by means fixed withrespect to said distributor cap, said insert'memher having a pluralityof circumferentially spaced electrodes that engage the outer electrodescarried by the body portion of said distributor cap and having anopening receiving said center electrode.

6. A distributor cap for an ignition distributor comprising, a generallycup-shaped body portion formed of electric insulating material, acurrent carrying center electrode and a plurality of outercircumferentially spaced electrodes carried by the top wall of said bodyportion, and an insert member formed of electric insulating materialrotatably supported by means fixed with respect to said distributor cap,said insert member carrying a plurality of circumferentially spacedelectrodes and having an opening receiving said center electrode, eachof said electrodes having a generally arcuately extending surface inengagement with a surface of the outer electrodes supported by the bodyportion of said distributor cap and having generally arcuately extendinglower surfaces adapted to cooperate with the contact means of a rotor.

7. A distributor cap for an ignition distributor comprising, a bodyportion formed of electric insulating material, said body portionsupporting a center current carrying electrode and a plurality of outercircumferentially spaced electrodes, and an insert member formed ofelectric insulating material, having an opening receiving said centerelectrode whereby said insert member is journalled for rotation directlyon said center electrode, said insert member having a plurality ofcircumferentially spaced electrodes that are in engagement withrespective outer electrodes carried by said body portion.

8, A distributor cap for an ignition distributor comprising, a generallycup-shaped body portion formed of electric insulating material, saidbody portion having a top wall supporting a current carrying centerelectrode and a plurality of outer circumferentially spaced electrodes,and an insert member formed of electric insulating material having anopening receiving said center electrode whereby said insert member isjournalled for rotation on said center electrode, said insert memberhaving a plurality of circumferentially spaced electrodes that passthrough the insert member, the top surfaces of the electrodes in saidinsert member being elongated and generally arcuately extending andcontacting a surface of the outer electrodes in said body portion, theelectrodes in said insert member having downwardly extending portionsformed with generally arcuately extending surfaces that are adapted tocooperate with contact means carried by a rotor of a distributor.

9. A distributor cap for an ignition distributor comprising, a bodyportion formed of electric insulating material, said body portionsupporting a center current carrying electrode and a plurality of outercircumferentially spaced electrodes, an insert member formed of electricinsulating material having an opening receiving said center electrodewhereby said insert member is journalled for rotation directly on saidcenter electrode, said insert member having a plurality ofcircumferentially' spaced electrodes that are in sliding engagement withrespective outer electrodes carried by said body portion, and interfitting means disposed respectively on said cap and insert member forpreventing cocking of said insert member.

10. The distributor cap according to claim 9 wherein the inter fittingmeans comprises an annular projection on the cap and an annular recesson the insert member which receives the annular projection on the cap.

11. A distributor cap for an ignition distributor comprising, a bodyportion formed of electric insulating material, said body portionsupporting a center current carrying electrode and a plurality of outercircumferentially spaced electrodes, an insert member formed of electricinsulating material having an opening receiving said center electrodewhereby said insert member is journalled for rotation directly on saidcenter electrode, said insert member having a plurality ofcircumferentially spaced electrodes that are in sliding engagement withrespective outer electrodes carried by said body portion, and re tainingmeans for retaining said insert member on said center electrode.

12. The distributor cap according to claim 11 wherein the retainingmeans includes a spring.

References Cited in the file of this patent UNITED STATES PATENTS2,525,180 Purdy et al Oct. 10, 1950 2,643,275 Saunders June 23, 19532,872,537 Hartzell et al Feb. 3, 1959 FOREIGN PATENTS 929,160 GermanyJuly 18, 1955

5. A DISTRIBUTOR CAP FOR AN IGNITION DISTRIBUTOR COMPRISING, A BODYPORTION FORMED OF ELECTRIC INSULATING MATERIAL, SAID BODY PORTIONSUPPORTING A CURRENT CARRYING CENTER ELECTRODE AND A PLURALITY OFCIRCUMFERENTIALLY SPACED OUTER ELECTRODES, AND AN INSERT MEMBER FORMEDOF ELECTRIC INSULATING MATERIAL ROTATABLY SUPPORTED BY MEANS FIXED WITHRESPECT TO SAID DISTRIBUTOR CAP, SAID INSERT MEM-